The Perfect Hybrid
by ShiroSoul95
Summary: Her mind froze when he took off the red cloth that covered his arm. Tohsaka Rin was furious. No, not at the red haired mage that stood in front of her. But at the winner of the 4th Holy Grail War. Furious and and sickened that the man had felt a need to make his son the perfect hybrid...of a human and Heroic Spirit. One-shot, may become a full fledged story based on feedback.


**Hey guys! Alright, you got me! I'm writing another story…maybe! I dunno, I just had this in mind for a while now after playing through HF route again. I just kept wondering what would happen if Shirou had Archer's arm since the beginning? How would things be different? More to talk about at the end for the authors note. Be sure to read, enjoy, and give feedback! See you at the end of the chapter.**

**Chapter 0: "Teaser"**

"Tohsaka!" Shriou shouted as he launched himself at her.

Rin's brain slowed down as she watched the familiar red headed boy leap towards her location. Before she could even process what happened she found herself flying through the air, carried by the Emiya boy in a bridal fashion. She didn't contemplate how he had ran up her so fast, crossing the distance almost instantaneously. She didn't question how he had seemingly jumped nearly 10 meters in the air in a single bound. She was thinking about how close she was to death, how her body and stiffened when she saw that black thing come at her like a cannon ball.

Blinking once she looked up to look at Emiya's face, a sinking feeling in her heart. A sudden crashing sound brought her mind back into focus as she realized that a crater suddenly erupted where she had previously stood. A writhing black mass stood at the center of it, traces of shadow-like smoke hugging the barely-recognizable human shape. It had clawed hands, reptilian like skin, and strange bone like armor covering its exterior. She felt her blood run cold as she stared into its blood shot glowing eyes.

Shirou landed softly several meters away from the edge of the crater.

"Are you alright? Tohsaka?" Shirou inquired as he looked down at the girl in his arms, eyes flickering back and forth between the beast and Tohsaka,

Tohsaka's eyes peeled off from the creature as she realized that they were on the ground. Her mind came up to speed as she realized what had just happened. Emiya had just saved her. She was about to be attacked by that black thing. And Emiya…

Tohsaka felt her face flush as she noticed several things. Her arms were gripping Emiya's neck tightly. Her head was against his chest as if it were glued. Rin's legs that went over his arms felt oddly comfortable.

Oddly enough, her brain was active enough to process embarrassment.

"PUT ME DOWN!" She shrieked as she fumbled, struggling to get out of her rather suggestive positioning, forgetting the severity of their situation for a moment. Shirou looked surprised for an instant, his golden eyes widening.

"We don't have time for this!" Emiya growled as he his hold on her tightened, his eyes suddenly hardening with a dull light.

Without warning Emiya shot sideways, causing Tohsaka to yelp in shock, pressing herself to his body as a furious flush arose on her cheeks. Barely seconds after he had moved, another explosion resounded through the empty street. Tohsaka looked around Shirou's elbow to see the black creature standing in the epicenter of another crater where they had previously stood, it's fist embedded in the ground.

"That's some crazy power," Emiya grunted as he started running.

Tohsaka dryly noted in her mind that his observation was fairly obvious. But she didn't dare say it out loud. She never dreamed that trying to catch a low-born magus who was running amok in her city would suddenly evolve into a fight of this magnitude. She just wasn't prepared for this. Mentally she berated herself. Why? Why couldn't she move? Was she so scared of a concept as simple as combat?

Why did she have to be saved by Emiya of all people?

Shirou paid her no attention as he focused on creating distance between himself and that thing. But every time he moved a bony-black fist would follow him, piercing the area they had just vacated. A deadly game of cat and mouse at high speed and high power.

Deafening sounds littered the night air as Emiya nimbly dodged the pursuing monster, jumping onto a light pole to evade the latest attack.

"Tohsaka it's chasing us into the park," Emiya stated, his voice not showing any fatigue despite the speed that he had maintained, piquing her curiosity slightly, "I don't think it wants to kill us."

"More like it can't kill us," Tohsaka added.

She tried to think. Why would a monster be chasing them into the park of all places? Cornering them in an alley way would be better to finish them off, with its master laying a trap. Her train of thought was interrupted as Shirou bent forward and jumped off of the light pole, moments later sounds of glass shattering came to her ears. That thing just kicked through steel like butter. This made classification of the creature much easier: whatever this thing was it was no simple wraith. It had physical abilities that actually materialized into the real world.

This made no sense! The master didn't even need to be present; the pure combat potential of this creature was enough to take down both Emiya and her. Rin blinked as her mind connected the pieces of information.

"It's bringing us to its master," she whispered. How dumb of her, how would Emiya hear this?

"Roger that," Shirou responded, indeed hearing her, "better made a quick short cut then." With a mighty push of his legs they flew to a side of a building. Shirou kicked off the wall as soon as they approached it, crossing over a street as the moon light illuminated their path. Shirou Reinforced his eyes as he spotted the tall trees of their destination off in near distance.

It didn't take long for them to reach the Fuyuki Memorial Park. Shirou landed on the street next to the park. He let Tohsaka down, blushing as he did all the while giving his best awkward smile. At least he had enough sense to be embarrassed as well.

They walked forward to the center lawn of the park, where the enemy was most definitely located. Tohsaka visibly relaxed when Shirou alerted her that they were no longer being pursued, for the time being anyway. As they approached the edge of the lawn Rin could see a figure standing there, hair blowing in late night wind. Rin could feel the blood lust even from here. But who was that?

"Sajyou-san" Emiya greeted, answering Tohsaka's question inadvertently, "I see you've been waiting for us."

Tohsaka was about to Reinforce her eyes to get a better view, but stopped at Emiya's words. Her mind processed the information. Sajyou was the only family that practiced formal-craft in Fuyuki. Tohsaka could have sworn that Kirei told her that the previous heads of the family (elder sister and father) had perished in the previous war. Then again, she wasn't surprised anymore to find random and unknown magus popping up over the city, Shirou was a prime example of it.

Tohsaka's thoughts returned to the girl in front of her as they walked close enough to get a good look at her.

The other girl was of similar age to Tohsaka. She had shoulder length black hair that was straight and lustrous, with neatly combed bangs covering her forehead. She wore wide rimmed glasses that overlaid bright blue eyes. She was wearing a similarly colored blue-hooded sweater over a white blouse. This was all complimented by short-shorts that were worn over leggings and finally brown leather boots covering her feet.

She was a beautiful girl, if not for the fact that Tohsaka could almost see the hate boiling behind those vibrant blue eyes. They didn't even waver when a black shadow landed next to her. So this Sajyou Ayaka was the master of the creature?

Tohsaka actually thought Ayaka was decent when she first met her.

"Sajyou-san," Tohsaka greeted with false-sweetness emphasizing the name, "Didn't know you were capable of creating a monster."

Tohsaka never knew her last name

"Tohsaka," Emiya reprimanded, "I don't thin-"

"I just summoned my familiar," Sajyou said, interrupting Shirou midsentence ,"Tohsaka-san"

Ayaka Sajyou spat the name out like it was poison.  
Tohsaka felt her eyes widen. The Sajyou line was supposed to be only capable of shamanic magic. Shamanic magic never had any summoning magic powerful enough to summon a creature that surpassed a ghoul, nevertheless having a physical body.

"Ayaka-san," Emiya started, "Why are you doing this? Why do you have a monster like that for a familiar? Why is it attacking people?"

"I would prefer if you left now Emiya-san," Ayaka breathed, exhaling those words, "There's no need to get yourself involved in this."

Shirou didn't respond, he just looked at Ayaka with concerned eyes. Eyes, that Ayaka was unable to look directly into, breaking contact after a moment. But his eyes sent a clear message to her: he wasn't going to leave that easily. Meanwhile Rin was breaking down the information. Ayaka wanted to face Tohsaka alone, so it means that Ayaka had some sort of beef with her. What could it be? Tohsaka went through all the interactions that the two may have had in the past. She kept drawing up a blank. There wasn't any time that the two families had even talked to the other, save for the initial allowance of letting the Sajyou setup a workshop in the city and…that…

That…really…important…thing

"I see," Rin sighed heavily, "It all comes back to that doesn't it?"

Ayaka's head jerked upwards, her eyes that were previously full of shame when looked at by Emiya were suddenly staring daggers at her. But she didn't answer.

"Is that why you're going around having your familiar steal life-energy? To gain enough prana to summon a Servant in the Holy Grail War?"

Tohsaka continued. But they weren't really questions. They were claims that only had to be verified now.

Ayaka didn't falter at the rush of questions. She continued her stare down. But her pretty pink lips opened, "Papa and Onee-san."

Tohsaka froze.

She had no idea why the previous head and heir had to do with this, but she had a pretty good idea what happened.

"Papa and Nee-san died in that damned war," Ayaka's words chocked, she was close to tears "We were happy. But being a Master is so prestigious. You get to summon a Hero, and have your wish fulfilled…."

Ayaka spoke, her voice getting stricter and stricter with each passing second, her word's trailing off

"-but no one ever mentions that you die. No one. And they did die. Papa and Nee-san. The Executor for the Church said that they were killed by another Master. Burnt. Incinerated. We didn't even get their bodies back."

Word's tumbeled out of the other girls mouth and Tohsaka spied a few streaks of sparkling liquid falling from her eyes.

"Ayaka-san, wait a sec-" Emiya, who had been silent for the entire transgression, moved his leg to take a step towards Ayaka.

"Don't come any closer!" Ayaka screamed, hugging herself and stopping Shirou in his tracks, " Emiya-san. Just go away. You have nothing to do with this. I don't want to hurt you."

Shirou didn't dare take a step forward.

"Ayaka-san, I'm already involved as it is," he said matter-of-factly, but he tried to urge her, "I don't care if you hurt me but I don't want you to hurt yourself."

Tohsaka sincerely hoped that Shirou could talk this girl out of her madness. That familiar thing could be anywhere, and she didn't trust the mental state of the girl enough to think that civilians wouldn't be getting hurt. They were in a bad position as is. Tohsaka looked over at Ayaka again. The girl was silent, but quivering. Her arms wrapped around herself as her knees were slightly bent.

Tohsaka bit her lip as silence reigned over the lawn. Neither side moving nor making a sound. Rin looked back at Emiya, whose face looked deathly serious. When he had said that he didn't want anyone to get hurt he was serious; going as far as to even care about the culprit.

"Why?"

A voice spoke out, barely a whisper. But the effect of the word was much greater than its volume. Tohsaka felt herself shiver as the air around them plummeted in temperature.

"Ayaka-san?" Shirou asked, his back straightening as his guard was raised. The wind whistled around them as suddenly black feathers started appearing out of thin air, covering Ayaka in a large vortex.

"Elder generation black magic?" Tohsaka asked as she raised an arm to cover her eyes.

"Whatever it is we need to move back, her prana is flooding the area."

Emiya responded as he retreated a few steps

Suddenly the vortex of feathers dissipated as quickly as it appeared. Tohsaka's stomach sank as she saw a familiar black thing next to Ayaka. There was no hope now. By the time the Church would even be alerted to the Magus' presence they'd all be splotches of red on the grass.

"I don't get it Emiya san," Ayaka said as she looked up at Shirou, "Why are you still near her? Why do you still trust her? It's all their fault you know? The Tohsaka, Makiri and Einzbern. All their fault."

Shirou didn't respond, his eyes never trailing off of Ayaka's form. He noticed a bandage around her wrist. But he let her speak, he needed to know what was wrong.

"They all wanted to pursue magic!" Ayaka screamed, tears falling rapidly now, "A selfish dream to try and replicate the Third Magic. People die…just so they can get their own wish. Well what about me?! My wish to live with my own family?! What about you Emiya-san?! You're a victim of this too!"

Tohsaka's mind stopped function, as she sincerely anticapted that the next line would not be what she was thinking it was going to be.

_**"Don't you resent them for losing your family like I did?!" **_

Tohsaka's heart froze. Emiya…lost his family in the previous war?

She remembered what he had said before: _I'm a survivor of that fire_.

Oh no.

She cast a glance at him, but his gaze was downward. He had nothing to say. She found herself stepping away from him.

"Don't worry Emiya-san. I'll get revenge for you as well. When I'm selected as Master and I win the Grail I'll bring back all those that died in the wars. Even your family," Ayaka said, as if trying to soothe the boy.

"But before that I need to make sure that I get rid of the competition"

Her words were like a trigger. The black monster next to her sprang into action. Launching itself at Tohsaka, clawed hand outstretched, aiming at her throat.

This was the end wasn't it? Tohsaka closed her eyes, there was nothing she could do. Her magic couldn't harm the creature. All she could do now was let death take her.

Or it should have…if Shirou didn't grab her hand and pull her towards himself.

"Emiya-kun?!" she asked incredulously.

But he wasn't looking at her. He was giving a hard gaze towards Ayaka. No, hard wasn't a good term. There was compassion and empathy in his eyes, but there was resolve.

"Sajyou-san…I did lose my family in that fire. But I gained a new one from it. I may have lost all that I had held. But now I have so much more. That fire made me, and I survive to give meaning to their deaths…as you living gives meaning to your father and sisters' death."

He spoke with conviction. As if he had rehearsed this before. As if he thought about this constantly.

Ayaka's eyes widened in surprise and then ended in confusion. She didn't know how to answer.

"Killing will only beget more killing. You won't become any better than those murders you condemn. There's no need for this. I won't stand in the way of innocents getting hurt."

"…So what to do you plan to do…Emiya-san?"

Ayaka, painfully, paced her words.

"I'll tell you. After I get rid of the power that's corrupted you."

Ayaka looked taken aback.

And then she laughed.

"I see! So no one understood me, not even you Emiya-san"

"I understand you well Ayaka-san, but that comes later."

Emiya spoke and walked forward, truly intending to fight.

"No mere human can take on my familiar! My familiar is born from my sorrow and hatred. It's the manifestation of my resolve."

Tohsaka stared at the moving back of the red haired mage she had barely met a year ago.

"There's no resolve when there's only hatred."

Final words were said. The coffin was sealed.

"Emiya-kun there's no need for this!"

Tohsaka tried to move forward. To stop Shirou from fighting that creature. It wasn't his place to do this. It was her family's fault! She didn't want anyone else to suffer for it.

Emiya looked over his shoulder at her, giving a brief confident grin, "I would be further back if I were you Tohsaka. Wouldn't want you to get hurt because you stood too close now, would we?"

Tohsaka felt herself blush all traces of doubt leaving her, Shirou never broke promises. All she could do was trust him. But she hated it so, "B-baka! She said no human can defeat it! You're going to go in to die!"

"Whoever said I was human?"

Chilling words stopped her mind, the previous euphoric emotion melting away.

What…had…he…just…said?

_Whoever said I was human?_

Emiya stepped forward, every step strengthening his tenacity as he inched closer to the beast. There was no point in holding back. This thing was powerful. Really powerful. So he would need armor. Some sort of armor that would protect him from the physical attacks as he would focus on defending. In his find he went through a mental catalogue of sorts as he found what he was looking for.

"Trace…on!"

He said his spell as he felt his circuit's flair to life. The image that he saw in his mind's eye was brought to reality.

Instantly objects appeared onto him, seemingly made out of air. Royal blue robes covered him, made from a thick material that flapped loudly in the wind. Polished steel covered his chest, reaching down to the top of groin, where it connected with straps to long side skirts that covered his waist. His left arm only had a shoulder plate and a single metallic glove. His right side was more heavily armored in comparison, with a full set of metal graves covering the entire length of his arm (**Essentially the armor of Saber from Fate/Prototype)**.

The armor gleamed ethereally silver under the moon light.

Shirou looked down at himself, confident in his creation, feeling the power of the legendary armor he had crafted from air. He raised his right arm and willed away the cloth and armor. The material burst into a shower of glowing particles.

And it revealed an arm, wrapped in a red cloth from the palm to the shoulder. Tohsaka felt an odd feeling pass up her spine as she looked at it.

"Sojyou-san…once I remove this Shroud, I can't guarantee your safety. Please stop while you can."

It was his last urge. They could avoid this fighting.

Ayaka would have none of it, she shook her heads and stood straight, "Amaymon! Kill him!"

The black monster turned towards him slowly.

Shirou took a deep breath in. There was no other choice. He pulled on the knot on the shoulder, letting the shroud fall away. The arm felt oddly naked to him, a by-product of wearing it over his arm constantly for almost 5 years. The arm was a darker shade of brown than Shirou's own, and strangely muscular. It hung in the air for several seconds, letting the cold air bite at it.

And then it hit him.

The pain.

The pain.

His mind was on fire. It was like someone stabbed his shoulder blade with a hot knife and all he could do was watch as it sank deeper into his body. All he could think about was the pain. But he endured it. He poured prana into his arm, ignoring the nausea that assaulted him. A rush of light erupted from the back of his mind as he felt the numerous godly circuits in his arm start glowing. He felt the prana flow down from his neck into his arm. And he saw it. The back of a broad shouldered man who looked over his shoulder at Shirou and smirked.

He was at the gate now. Everything was practiced from this point on.

And as his father had taught him so many years ago, Shirou reached past that wall of light. Past the back of that man. He needed to surpass him to reach the bounty of knowledge that was trapped on that other side. That's all he needed to do, endure the pain as he grasped for that power. He needed that power. His mind wasn't weak anymore, years of wearing the arm had given him a resistance of sorts. It wasn't perfect but he was able to do this now. He needed to do this now. Shirou kept pumping in the mana.

Tohsaka's eyes widened in utter disbelief as waves of prana washed over her. Emiya wasn't capable of this. Whenever he used magic it was like she was pricked by a small flame. Isolated and warm, but dangerous if you got too close. But this feeling was indescribable. She felt as if she was being stared down by a colossus, a fear that dwarfed the aura the Ayaka familiar exuded.

_Emiya-kun, what are you?_ Tohsaka thought to herself.

But Emiya didn't pay attention to the girl behind him. The very atmosphere he created with his unleashed arm froze Ayaka and her familiar in their tracks. Emiya stared at the creature. His eyes suddenly steel gray color and his red hair suddenly transforming into white strands. His skin tone darkened, matching the color of his left arm.

_EMPATHY POINT REACHED_

He was given permission. The arm had given him access.

His eyes performed Structural Grasping, comparing the creature in front of him to the data-vault that he now had admission too. It was a demon. A ghoul of sorts that was created from cadavers and human blood. Earliest point of reference was the demon summoning rituals of Gilles de Rais. A demon was allowed to possess a dead body and change the shape of the dead flesh around it. It managed to avoid rigor mortis by using prana from its master and repaired itself with prana from the master as well.

His mind automatically came up with an appropriate response. Christian weapons would work, as well as verses from the Bible. So he needed a blade of exorcism of the highest class. Black-keys wouldn't be enough to sever the connection from the other world.

He needed…

"Trace on!"

He needed to delve into the library that the arm had given him. He did not know any weapon of such caliber…but the arm did. He was sure the arm did.

_Objective acknowledged. Suitable blueprint located._

He mentally saw himself reaching into the arm and grabbing something. He needed to pull it out.

_Judging the concept of creation._

_Hypothesizing the basic structure._

_Duplicating the composition material._

_Imitating the skill of its making._

_Sympathizing with the experience of its growth_

_Reproducing the accumulated years _

_Excelling every manufacturing process_

There. His fingers closed around a hilt of a blade. A sense of déjà vu assaulted him as the feeling of a familiar but unfamiliar weight of the sword in his hands was received by his body He swung it sideways several times, naturally assimilating with the weapon he had never held before. He understood the weapon perfectly. Its balance point, it's length, it's hilt weight, it's materials, everything. He had created Durandal. The holy sword of Sir Roland himself. Blessed by his king and given the ability to perform three miracles due to the grace of God.

It was perfect. A perfect mimicry.

"Let's get started," Shirou found himself saying. He gazed over at the creature in front of him and moved. The creature responded similarly quickly.

Shirou swung the blade heavily, the gleaming dark steel of the blade hungrily approaching its opponent. The creature dodged the first slash with inhuman grace, twisting it's abdomen out of the way as it lashed out with a back hand. Shirou didn't even bother trying to evade the attack, the clawed hand of the demon bouncing harmlessly off his chest plate. The demon wasn't prepared for this, its attack was stopped and the subsequent opening wasn't planned.

Emiya wasted no time, as he swung again with supernatural speed and accuracy. The monster barely managed to deflect the second swing as a third and a fourth came just as quickly. Shirou started grinning. He hated the sickening feeling of arrogance that started to arise in his throat. The feeling of total dominance over your opponent. It didn't help that the more Shirou waved the weapon the more he started to realize that his movements weren't his own. He just moved in the ways that the sword was telling him. The sword was teaching him how to move, instructing him how to attack.

Shirou wouldn't look a gift horse in the mouth, however. He let the sword control him, his body naturally evading and attacking with deadly accuracy as he swung and stabbed the creature. For the demon's credit it was doing rather well, being able to deflect and parry the attacks with its bare claws and a shower of sparks.

But it couldn't do it forever.

Shirou saw the mistake it made in slow motion. He swung Durandal in an arc towards the stomach of the monster. As it stepped backwards it's foot hit the ground awkwardly.

There.

Emiya he lowered his plated shoulder and instinctively Reinforced his body, then proceeding to smash the monster's chest.

The mere force of the physical attack sent the monster flying.

But the fight wasn't over. Shirou would never give the demon a moment's respite. Before the familiar had even touched the ground from its fall Shirou had already crossed the distance. He lifted a plated leg and struck the monster on its side. The monster had raised its arms to block the blow, but it was futile.

Tohsaka felt her stomach turn over at the sickening sound of bones snapping like twigs.

The black familiar had hit a tree trunk, implanting its form onto it, the tree shaking worryingly.

All was quiet.

The familar wasn't moving. But Shirou was, towards it blade held at an angle to his side.

"Durandal!" he called, "I beseech thy holy name! May your blessed edge cut these demons before me!"

The dark steel blade started glowing with an ethereal light, in response to its wielder's wish.

And he swung.

**And there we have it. What do you think? Good? Bad? I personally think my writing is trash for this because it was so rushed and I'm bad at fight scenes. But I like the general idea of the plot. What I had in mind was that Kiritsugu summons Archer EMIYA during the Fourth Holy Grail war. At the end of the war Kiritsugu orders Archer EMIYA to destroy the Grail. As always the plan backfires and we have the Fuyuki Fire.**

**What's different is that Shirou lost his arm in his accident as a child when a piece of re-bar falls on top of his left shoulder splitting it. Shirou is now in a fire, losing blood, and losing sanity. Kiritsugu finds the child, gives him Avalon, but Archer appears before him. Archer tells Kiritsugu that the boy is him in the future and explains briefly what will happen. Kiritsugu doesn't want Illya to suffer the same fate as Ira so he agrees to Archer's plan to graft the arm onto the child.**

**Still working out the plot kinks, and depending on feedback I might make it a full-fledged story. Please tell me what you think!**


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